Why datagridview doesnt work in vb.net?

Question

I have written code to show records in a datagridview but it shows nothing. I have tried to debug & when it step into GetData function following codes

Catch ex As Exception  
returnData = Nothing  
If connection.State = ConnectionState.Open Then  
    connection.Close()  
End If

become gray & it shows error sign. When I take my mouse pointer on it it shows message. It says "Cannot open database SUIMT requested by the login. The login failed. Login failed for user 'MY-PC\James'". Please check my code & help me to get rid of this problem & dont forget to add example with your answer.

Necessary information : I am using SQL SERVER 2000 PERSONAL EDITION. Name of my database is "SUIMT" & table which I want to show in datagridview is called "monthly_instal".

Imports System.Data.SqlClient

Public Class Form34

Private Const ConnectionString As String = "Server=.\SQLEXPRESS;" & _ "Database=SUIMT;Trusted_Connection=True"

Private Sub Form34_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

cmbdmiid.Items.Clear() 
cmbdmiid.Text = "ID NUMBER" 
cmbdmidt.Items.Clear() 
cmbdmidt.Text = "DATE" 
txtdmiron.Text = "ROW NUMBER" 
con = New ADODB.Connection 
con.Open("Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=SUIMT") 

rst = New ADODB.Recordset

With rst .Open("Select * From monthly_instal", con, ADODB.CursorTypeEnum.adOpenStatic, ADODB.LockTypeEnum.adLockReadOnly)

        If .BOF = False Then 
        .MoveFirst() 
        While .EOF = False 
            If Not cmbdmiid.Items.Contains(.Fields("stu_id").Value) Then 
                cmbdmiid.Items.Add(.Fields("stu_id").Value) 
            End If 
            .MoveNext() 
        End While 
    End If 
    .Close() 
End With 

rst = New ADODB.Recordset

With rst .Open("Select * From monthly_instal", con, ADODB.CursorTypeEnum.adOpenStatic, ADODB.LockTypeEnum.adLockReadOnly)

     If .BOF = False Then 
        .MoveFirst() 
        While .EOF = False 
            If Not cmbdmidt.Items.Contains(.Fields("dt").Value) Then 
                cmbdmidt.Items.Add(.Fields("dt").Value) 
            End If 
            .MoveNext() 
        End While 
    End If 
    .Close() 
End With 

Me.CREATEUSERToolStripMenuItem.Enabled = False 
Me.DELETEUSERToolStripMenuItem.Enabled = False 
Me.CHANGEPASSWORDToolStripMenuItem.Enabled = False 
Me.ASSIGNPERMISSIONToolStripMenuItem.Enabled = False 
Me.SHOWALLToolStripMenuItem.Enabled = False 
Me.CREATEACADEMICYEARToolStripMenuItem.Enabled = False 
Me.DELETEACADEMICYEARToolStripMenuItem.Enabled = False 
Me.CREATESESSIONToolStripMenuItem.Enabled = False 
Me.DELETESESSIONToolStripMenuItem.Enabled = False 
Me.CREATEDEPARTMENTToolStripMenuItem.Enabled = False 
Me.DELETEDEPARTMENTToolStripMenuItem.Enabled = False 
Me.CREATEEXAMTYPEToolStripMenuItem.Enabled = False 
Me.DELETEEXAMTYPEToolStripMenuItem.Enabled = False 
Me.CREATESUBJECTToolStripMenuItem.Enabled = False 
Me.DELETESUBJECTToolStripMenuItem.Enabled = False 
Me.ADMISSIONToolStripMenuItem.Enabled = False 
Me.DELETEADMISSIONToolStripMenuItem.Enabled = False 
Me.ADMISSIONREPORTToolStripMenuItem.Enabled = False 
Me.STUDENTINFORMATIONToolStripMenuItem.Enabled = False 
Me.DELETESTUDENTINFORMATIONToolStripMenuItem.Enabled = False 
Me.SEARCHSTUDENTINFORMATIONToolStripMenuItem.Enabled = False 
Me.STUDENTINFORMATIONREPORTToolStripMenuItem.Enabled = False 
Me.CREATESTUDENTRESULTToolStripMenuItem.Enabled = False 
Me.DELETESTUDENTRESULTToolStripMenuItem.Enabled = False 
Me.STUDENTRESULTREPORTToolStripMenuItem.Enabled = False 
Me.RESULTSHEETREPORTToolStripMenuItem.Enabled = False 
Me.CREATEMONTHLYINSTALLMENTToolStripMenuItem.Enabled = False 
Me.DELETEMONTHLYINSTALLMENTToolStripMenuItem.Enabled = False 
Me.MONTHLYINSTALLMENTREPORTToolStripMenuItem.Enabled = False 
Me.CREATEBALANCESHEETToolStripMenuItem.Enabled = False 
Me.DELETEBALANCESHEETToolStripMenuItem.Enabled = False 
Me.BALANCESHEETREPORTToolStripMenuItem.Enabled = False 
Me.ABOUTTHISPROGRAMToolStripMenuItem.Enabled = False 
Me.EXIToolStripMenuItem.Enabled = False 

End Sub

Public Function GetData() As DataTable Dim SelectQry = "Select row_num, stu_id, tot_amou, paid, du, aoins, due, dt From monthly_instal where stu_id = '" & cmbdmiid.Text & "' AND dt = '" & cmbdmidt.Text & "'"

Dim connection As New SqlConnection(ConnectionString) 
Dim returnData As New DataTable("monthly_instal") 
Try 
    connection.Open() 
    Dim command As New SqlCommand(SelectQry, connection) 
    Dim adapter = New SqlDataAdapter(command) 
    adapter.Fill(returnData) 
    con.Close() 
Catch ex As Exception 
    returnData = Nothing 
    If connection.State = ConnectionState.Open Then 
        connection.Close() 
    End If 
End Try 
Return returnData 

End Function

Private Sub butdmiclo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butdmiclo.Click speak34.Speak("Delete monthly installment window has been closed successfully") Me.Close() End Sub

Private Sub cmbdmidt_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmbdmidt.Leave dtg1.DataSource = Nothing dtg1.DataSource = GetData() End Sub End Class

Necessary information : Name of my computer is MY-PC. When I am clicking on SQL SERVER SERVICE MANAGER it shows SERVER - MY-PC. I guess MY-PC must be used as a server name. As a result I used it

Private Const ConnectionString As String = "Server=.\MY-PC;" & _ "Database=SUIMT;Trusted_Connection=True"

But it shows error. It says "An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)"

I am confused it says error has occurred to create connection with SQL SERVER 2005! But I need to connect it with SQL SERVER 2000. Yes I have SQL SERVER 2000 & 2005(SQL SERVER 2005 was installed with Visual studio). But I am using SQL SERVER 2000.